metadesk/tests/grammar.md

/* MetaDesk grammar with semantic annotations *

• Each line represents a BNF-esque production of the form:

•  symbol : rule_1 | ... | rule_n
  

• • Pipe signs indicate mutually exclusive alternatives
• • Square quotes denote optional rules
• • Character literals are terminal productions
• • Tags indicate which way the productions attach to the generated tree (@child, @sibling, @leaf, @tag)
• and miscellaneous semantics (@delimiter) */

file : [@child set_list] set_list : tagged_named_set [' ' @sibling set_list] tagged_named_set: { [tag_list] set } tag_list : @tag tag ' ' [tag_list] tag : '@' identifier // TODO(mal): tag parameters set : @leaf leaf | '{' [@child set_list] '}' leaf : identifier | integer_literal | char_literal | string_literal // TODO(mal): Also symbol_label identifier : alpha [alphanumeric] // TODO(mal): I think we should allow leading underscores alphanumeric : alpha [alphanumeric] | digit [alphanumeric] | '_' [alphanumeric]

integer_literal : { ['-'] natural_literal } natural_literal : digit [natural_literal]

char_literal : @delimiter ''' [char_literal_items] @delimiter ''' char_literal_items : char_literal_item [char_literal_items] char_literal_item : ascii_no_backslash_no_quotes | '"' | '\' ascii ascii : ascii_no_backslash_no_quotes | ''' | '"' | '\' ascii_no_backslash_no_quotes : digit | alpha | symbol_no_backslash_no_quotes | space symbol_no_backslash_no_quotes : symbol_no_backslash_no_quotes_1 | symbol_no_backslash_no_quotes_2 symbol_no_backslash_no_quotes_1 : '!'|'#'|'$'|'%'|'&'|'('|')'|'*'|'+'|','|'-'|'.'|'/'|':'|';' symbol_no_backslash_no_quotes_2 : '<'|'='|'>'|'?'|'@'|'['|']'|'^'|'_'|'`'|'{'|'|'|'}'|'~'

string_literal : @delimiter '"' [string_literal_items] @delimiter '"' string_literal_items : string_literal_item [string_literal_items] string_literal_item : ascii_no_backslash_no_quotes | ''' | '\' ascii

digit : '0'|'1'|'2'|'3'|'4'|'5'|'6'|'7'|'8'|'9' alpha : lowercase | uppercase lowercase : 'a'|'b'|'c'|'d'|'e'|'f'|'g'|'h'|'i'|'j'|'k'|'l'|'m'|'n'|'o'|'p'|'q'|'r'|'s'|'t'|'u'|'v'|'w'|'z'|'y'|'z' uppercase : 'A'|'B'|'C'|'D'|'E'|'F'|'G'|'H'|'I'|'J'|'K'|'L'|'M'|'N'|'O'|'P'|'Q'|'R'|'S'|'T'|'U'|'V'|'W'|'Z'|'Y'|'Z' space : ' '

symbol_label : '~'|'!'|'%'|'^'|'&'|'*'|'+'|'-'|'/'|'|'|'<'|'>'|'$'|'='|'.'|'?'|'_'|'\'

/*

symbol_no_quote : symbol_label | symbol_colon | symbol_group

symbol : symbol_label | symbol_colon | symbol_group

symbol_group : symbol_open | symbol_close symbol_open : '(' | '[' | '{' symbol_close : ')' | ']' | '}'

escaped_char : '\' '\' | '\' ''' | '\' '"' symbol_colon : ':'

*/

/* // NOTE(mal): I think this one should work too, but MD only delimits top level constructs with newlines file : [@child set_list] set_list : set [',' @sibling set_list] set : @leaf element | '{' [@child set_list] '}' element : 'A'

// NOTE(mal): This is the simples grammar that works
file            : [@child set_list]
set_list        : set ['\n' @sibling set_list]
set             : @leaf element | '{' [@child set_list] '}'
element         : 'A'

*/